A. Rachev, S.E. Greenwald - University of Pittsburgh JC.pdf · 2013-11-27 · Definitions Residual...
Transcript of A. Rachev, S.E. Greenwald - University of Pittsburgh JC.pdf · 2013-11-27 · Definitions Residual...
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A. Rachev, S.E. Greenwald
Journal Club 6.4.2009Eunice Yi
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Definitions
Residual strain : strain that exists in a solid when all external loads are removedOpening Angle (OA) : used to measure circumferential residual strain; angle formed by intersection of lines from the ends of the open inner arc at the midpoint of the inner arcStretch ratio (λ) : ratio of change in length
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Measurement of residual strain
zero-stress state no load state- Residual circumferential stress ratio λθ- Residual circumferential Green strain eθ
ri
ro
α
Ri
Ro
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Y.C. Fung
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Experimental setupCamera
Container with
medium
Temp control
Tube
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Measuring OA
Rapid initial opening followed by more gradual openingEffect of temperature not significantRings are actually non-circular
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Effects of residual strain
Homogenize circumferential stress distributionIncrease arterial lumen, wall tension, and mean circumferential stressDecrease wall shearIncreases compliance
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Growth
Arteries sensitive to alterations in mechanical environmentLong-term response to changing environmentChanges of arterial geometryVolumetric growth
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OA Patterns
General pattern : fall in OA towards periphery of subjectSmooth muscle contractionBirth to puberty/After puberty (in rats)Induced hypertension
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Obtaining zero stress stateOne radial cut vs. additional circumferential cut
Fung/Liu Vossoughi
Porcine Aorta
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My research
Characterize growth in native ovine pulmonary trunk tissueHow different aspects change with growth
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Connection to tissue engineering
Ultimate goal is to have engineered tissue mimic growth of native tissueApplications: pediatric valve replacements